#!/usr/bin/env python

# Copyright 2012 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Logs information about method execution."""

import logging

__author__ = 'Maciej Machulak'
__maintainer__ = 'Maciej Machulak'
__email__ = 'mmachulak@google.com'

__copyright__ = 'Copyright 2012, Google Inc.'
__license__ = 'Apache License 2.0'
__version__ = '0.2'
__status__ = 'Prototype'

_CRITICAL = 50
_ERROR = 40
_WARNING = 30
_INFO = 20
_DEBUG = 10
_NOTSET = 0

_LOG_LEVELS = {}


def __setup_loggable():
  _LOG_LEVELS['critical'] = _CRITICAL
  _LOG_LEVELS['error'] = _ERROR
  _LOG_LEVELS['warning'] = _WARNING
  _LOG_LEVELS['info'] = _INFO
  _LOG_LEVELS['debug'] = _DEBUG
  _LOG_LEVELS['notset'] = _NOTSET


def loggable(method='', level='debug'):

  def inner_loggable(handler):

    def log_execution(self, *args):
      log_level = _LOG_LEVELS[level]
      if log_level:
        if method != '':
          logging.log(log_level,
                      '--- starting executing method \'%s\' with name '
                      '\'%s\' ---',
                      handler.__name__, method)
        else:
          logging.log(log_level,
                      '--- starting executing method \'%s\' ---',
                      handler.__name__)
        handler(self, *args)
        logging.log(log_level,
                    '--- finished executing method \'%s\' with name '
                    '\'%s\' ---',
                    handler.__name__, method)
      else:
        raise LevelError(
            'required log level does not exist: %s' % level)

    return log_execution

  return inner_loggable

__setup_loggable()


class LevelError(Exception):
  """Raised if there is an error with getting the required level of logging."""

  def __init__(self, msg):
    Exception.__init__(self)
    self.msg = msg

  def __str__(self):
    return repr(self.msg)


def setup():
  var_dict = globals()
  var_dict['log'] = loggable()
